Combination debris collection and visual validation assembly

ABSTRACT

A method and apparatus for efficient and effective collection of debris from a wellbore, while permitting simultaneous visual verification of such debris collection. A debris collection assembly comprises a combination of one or more of the following: a reverse circulation assembly, a video assembly and at least one filter assembly. Fluids are circulated into a wellbore annular space via the reverse circulation assembly, into the video assembly where fluid and any associated debris are visually sensed and recorded, into the filter assembly where debris is separated from the fluids and collected, before cleaned fluids are circulated out of the wellbore. The components of the debris collection assembly are substantially modular, and can be run in combination with conventional wellbore cleaning tools (such as, for example, workstring-conveyed brushes, scrapers and/or magnets).

PRIORITY CLAIM AND INCORPORATION BY REFERENCE

This application claims the benefit of, and priority to, U.S. provisional patent application Ser. No. 61/865,169 filed Aug. 13, 2013. The entire disclosure of this provisional application is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to a method and apparatus for the collection of debris, as well as visual validation of said debris collection, from a wellbore such as, for example, during a well drilling operation. More particularly, the present invention pertains to a method and apparatus for efficient and effective collection of debris from a wellbore, while permitting simultaneous video verification of said debris collection prior to removal of said debris from said wellbore.

2. Brief Description of the Prior Art

During the operation and servicing of oil and gas wells, and particularly during well drilling operations, a wellbore environment can include drilled rock cuttings, milled metallic solids and/or other debris. Such materials can negatively impact efficiency of drilling operations and productivity of subterranean formations. Such materials can also negatively impact the effectiveness of other downhole operations and prevent downhole tools from operating properly.

Various equipment and techniques have been developed for removal of debris from wellbore environments including, without limitation, so-called “junk baskets”. Generally, conventional junk baskets are conveyed via tubular workstring or continuous cable or wireline into a wellbore having drilling fluids contaminated with solid debris. Such solid debris is collected within a basin or void in said junk basket. Thereafter, said junk basket (as well as any debris contained therein) is removed from said wellbore. The process can be repeated until a desired amount of debris has been removed from said wellbore.

However, various problems plague the use of conventional junk baskets and/or other debris collection equipment, as well as methods of using said equipment. Such problems include improper positioning of said debris removal equipment within a wellbore and, in particular, positioning of such equipment relative to debris to be collected and removed. Improper positioning of debris collection equipment within a wellbore—and especially relative to debris to be captured—can result in less than optimal debris collection performance.

Generally, positioning of debris collection equipment within a wellbore can be estimated using known information in order to gather maximum debris. However, such estimation methods are imprecise and often yield less than optimum results. Moreover, the effectiveness of conventional debris collection devices and methods can only be verified by physical inspection and analysis of debris after a collection device has been retrieved from a wellbore. As a result, such conventional debris collection equipment must often be conveyed in and out of a wellbore multiple times in order to evaluate collection efforts, thereby resulting in unnecessary trips in and out of wellbores and inefficient and expensive well operations.

Verification of wellbore debris collection and resultant “cleanliness” is critically important because it can greatly reduce or eliminate the likelihood of unnecessary pipe or wireline trips in and out of a well. Such unnecessary trips can be extremely expensive, particularly on rigs operating in deep water environments or other remote locations. In addition to economic concerns, such unnecessary pipe or wireline trips create additional safety hazards for personnel. By eliminating unnecessary trips, and especially pipe trips, safety hazards can be significantly mitigated.

Thus, there is a need for a method and apparatus for monitoring and validating wellbore debris collection operations providing effective and efficient debris removal from wellbores. Said debris collection should provide important information regarding effectiveness of said debris collection efforts, while eliminating unnecessary trips in and out of wellbores.

SUMMARY OF THE INVENTION

The present invention comprises a method and apparatus for collection of solid debris, as well as the visual validation of said collected debris, from a wellbore containing drilling mud, brine, completion fluid or other drilling fluid (referred to herein collectively as “well fluids”) as well as said solid debris.

The debris collection assembly of the present invention can be attached to a tubular workstring in order to be conveyed in and out of a wellbore, and manipulated within said wellbore; in such configuration, an annular space is formed between the external or outer surface of said workstring (and debris collection assembly) and the inner surface of the surrounding wellbore. The debris collection assembly of the present invention can comprise a modular design to increase debris-carrying capacity, and can be run in combination with other wellbore cleaning tools (such as, for example, workstring conveyed brushes, scrapers and/or magnets).

In a preferred embodiment, a debris collection assembly of the present invention comprises a combination of one or more of the following: a reverse circulation sub assembly (sometimes “RCSA”), a video sub assembly (sometimes “VSA”) and at least one filter sub assembly (sometimes “FSA”). Debris is captured within said debris collection assembly via circulation of wellbore fluids and, typically, reverse circulation in a localized section of wellbore in the vicinity of said debris collection assembly.

In a preferred embodiment, well fluids are pumped into an internal flow bore of a tubular workstring and diverted through said RCSA into said casing annular space. Well fluids containing debris are then circulated through said annular space and back into the workstring internal diameter through said VSA; debris is carried by increased fluid velocity into the internal diameter of the VSA.

Debris is removed from the well fluid stream using at least one FSA having a screen, slot(s), or other similar filtering device, as well as a magnet for capturing ferrous materials. Multiple FSA's can be utilized such as, for example, when multiple successive filtration subs are to capture smaller and smaller debris. In the event that said at least one FSA becomes blocked or clogged with debris, a bypass feature can activate, allowing fluid circulation to bypass said at least one FSA. Clean fluid exits said at least one FSA and re-enters the RCSA, thereafter returning to the earth's surface via a conventional wellbore circulation path through said casing annular space.

A preferential fluid circulation path can be controlled by directing fluid flow volume through said RCSA using an annular ring brush disposed on the outer surface of said RCSA between lower and upper circulating ports. Said annular ring brush limits annular fluid flow volume through said RCSA, resulting in a preferential flow path as described herein, without the use of a downhole annular sealing method such as a packer or swab cup.

Debris collection and removal from within a wellbore can be verified by means of at least one camera positioned within said VSA having a field of vision. In a preferred embodiment, said VSA can further comprise an onboard power supply, a lighting device, and electronic memory. By way of illustration, but not limitation, said at least one camera can be positioned adjacent to an internal flciw bore extending through said VSA, such that debris, entering said VSA can be recorded (via visual images and/or video) in said field of vision of said at least one camera.

The field of vision of said at least one camera can be illuminated by a lighting device, or a lighting system, disposed parallel with said at least one camera, or in any manner that agrees with a desired field of view of said camera. Additionally, said at least one camera of the present invention can comprise an electronic memory chip or other memory device that beneficially provides said camera with sufficient memory to record and store a plurality of visual images or videos that can be reviewed for validation of wellbore cleanliness and effectiveness of debris removal operations.

By way of illustration, but not limitation, retrieval of visual images and/or video data from said debris collection assembly can be accomplished by a variety of different methods, such as for example: wireless transmission of data from said VSA to a recording/display device, particularly at or near the earth's surface; transmission of data from said VSA to a recording/display device via a wired connection, particularly at or near the earth's surface; direct extraction or download of data from electronic memory of said VSA to a separate electronic memory device via wired or wireless data transmission; and/or transmission of data from said VSA to a receiver conveyed on wireline and positioned in proximity to said debris collection assembly via wired or wireless transmission.

The VSA can include a rotatable external sleeve that allows for convenient access to said video camera when the VSA is on surface. Said rotatable external sleeve includes an elongate slot having approximately the same width and length dimensions as the downhole camera. When access to said camera is desired, said external sleeve can be rotated into alignment with the camera so that the camera is accessible, such as for removal or maintenance.

The debris collection assembly of the present invention can also be run in combination with other data sensors, in addition to a camera. Additionally, the debris collection assembly of the present invention can be powered by any number of different methods including, but not necessarily limited to, surface fluid pump pressure, manipulation of a tubular workstring, and/or downhole fluid pump(s) located within said assembly.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

The foregoing summary, as well as any detailed description of the preferred embodiments, is better understood when read in conjunction with the drawings and figures contained herein. For the purpose of illustrating the invention, the drawings and figures show certain preferred embodiments. It is understood, however, that the invention is not limited to the specific methods and devices disclosed in such drawings or figures.

FIG. 1 depicts a side view of a reverse circulation sub assembly of the present invention.

FIG. 2 depicts a side sectional view of a reverse circulation sub assembly of the present invention.

FIG. 3 depicts a side sectional view of a filter sub assembly of the present invention.

FIG. 4 depicts a side sectional view of a video sub assembly of the present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

In a preferred embodiment, a debris collection assembly of the present invention comprises a substantially tubular configuration. A female or “box end” threaded connection member can be disposed at one end of said debris collection assembly, while a male “pin end” connection member can be disposed at the opposite end of said debris collection assembly. Following convention in the oil and gas industry, said threaded connection members can be used to include said debris collection assembly within a tubular workstring inserted into a wellbore such as, for example, drill pipe or the like.

In a preferred embodiment, debris collection assembly of the present invention comprises a combination of one or more of the following: a reverse circulation sub assembly (sometimes “RCSA”), a visual verification or video sub assembly (sometimes “VSA”) and at least one filter sub assembly (sometimes “FSA”). The debris collection assembly of the present invention can further comprise a substantially modular component design that can be run in combination with other wellbore cleaning tools (such as, for example, workstring-conveyed brushes, scrapers and/or magnets).

FIG. 1 depicts a side view of a reverse circulation sub assembly or RCSA 100 of the present invention. Said RCSA 100 generally comprises top sub 101, ported sub 103, and bottom sub 105. Centralizer 107 and ring brush 108 are disposed between top sub 101 and bottom sub 105, and extend radially outward from ported sub 103.

FIG. 2 depicts a side sectional view of reverse circulation sub assembly or RCSA 100 of the present invention. Top sub 101 has central flow bore 111 extending through said top sub 100, as well as female or box end-threaded connection 110. Said box-end threaded connection 110 which can be used to threadedly connect RCSA 100 to a tubular workstring, frequently but not exclusively at the distal or lower end of said workstring. Top sub 101 is connected to ported sub 103 using mating threads 122, while O-ring 123 provides a fluid pressure seal between said top sub 101 and ported sub 103.

Ported sub 103 generally comprises a tubular body member having a central flow bore 112 extending there through. Flow diverter, assembly 104 is disposed within said central flow bore 112; flow diverter assembly 104 has central flow bore 124 extending through said flow diverter assembly 104. Ports 113 extend through said flow diverter assembly 104, while aligned lower ports 116 extend through ported sub 103. Said flow diverter assembly 104 also connects to bypass tube 102, which forms a fluid pressure seal against the inner surface of central flow bore 111 of top sub 101.

Flow diverter assembly 104 is held in place within bore 112 of ported sub 103 using trapped socket head cap screw(s) 106 (which can be beneficially oriented in a radial pattern). Socket head cap screw(s) 106 locates ports 113 of said flow diverter assembly 104 with respect to lower flow ports 116 of ported sub 103, while providing constraint against axial movement of said flow diverter assembly 104.

Flow diverter assembly 104 further contains inner seat profile 114. Seat profile 114 can receive an activation ball or other dropped object (not shown in FIG. 2) which can be launched or dropped (such as from the earth's surface) through the inner bore of a tubular workstring until reaching RCSA 100. Said ball or other droppable object can eventually land on said seat profile 114, thereby obstructing a fluid flow path through central flow bore 124 of said flow diverter assembly 104.

Ported sub 103 has lower ports 116 that align with ports 113 of flow diverter assembly 104. Said ported sub 103 further connects top sub 101 to bottom sub 105, and provides a shouldered area for ring brush 108 and centralizer 107 which are disposed on the other surface of said ported sub 103 and extend radially outward therefrom.

Inner bore 111 of top sub 101 cooperates with bypass tube 102 to form an annular area 117. A fluid pressure seal is formed between said Inner bore 111 of top sub 101 and bypass tube 102 using an elastomeric seal or o-ring 118. Upper return fluid ports 115 extend from said annular area 117 through top sub 101.

Bottom sub 105 has central through bore 120 and lower pin-end threaded connection 119. Lower threaded connection 119 can be used to connect RCSA 100 to lower components of the debris collection assembly of the present invention (such as, for example, an FSA). Centralizer 107 provides protection for ring brush 108 and centralizes the assembly with respect to the inner surface of a surrounding wellbore (typically casing). Ring brush 108 provides an annular flow path restriction to help insure localized reverse circulation with minimal operational risk compared to swab cups or the like.

When the debris collection assembly of the present invention is being conveyed into a wellbore via a tubular workstring or otherwise, well fluids are able to bypass said RCSA 100 through communicated upper and lower circulation ports, as well as aligned central flow bores of top sub 101, bypass tube 102, ported sub 103, flow diverter assembly 104 and bottom sub 105.

After said debris collection assembly has been deployed to a desired location within a wellbore, a ball or other droppable object (not depicted in FIG. 2) can be dropped or launched within the internal bore of said workstring. Said ball eventually lands and seats on seat profile 114 of flow diverter assembly 104 within said RCSA, blocking a fluid flow path through central flow bore 124 of flow diverter assembly 104, and forcing circulated well fluids to flow through aligned ports 113 of said flow diverter assembly 104 and lower ports 116 of ported sub 103.

After said ball or other droppable object has been seated on seat 114, well fluids are pumped into an internal flow bore of a tubular workstring and diverted through said RCSA. Specifically, said fluids pass through aligned ports 113 of flow diverter assembly 104 and lower ports 116 of ported sub 103, and into annular space between the outer surface of RCSA and the inner surface of the surrounding wellbore. Said fluid passes through said VSA and FSA for visual verification and debris removal as discussed more fully below.

Clean fluid (i.e., well fluid with debris removed) eventually re-enters RCSA 100 via central through bore 120 of lower sub 105, as well as central through bore 112 of ported sub 103. Such fluid enters through internal ports 121, flows through channels passing through the body of flow diverter assembly 104 (said channels not depicted in FIG. 2), which extend into to annular area 117. Thereafter, fluid flows from said annular area 117 through upper ports 115 in top sub 101, returning to the earth's surface via a conventional wellbore circulation path through said casing/workstring annular space.

A preferential fluid circulation path can be controlled by directing fluid flow volume through said RCSA 100 using annular ring brush 108 having radially extending bristles disposed on the outer surface of ported sub 103 between lower ports 116 and upper ports 115. Said annular ring brush 108 limits annular fluid flow volume through said RCSA 100, resulting in a preferential flow path as described herein. The density and rigidity of the brush bristles create a sufficient restriction to direct annular fluid flow exiting said RCSA 100 in the casing annulus toward said VSA. Additionally, said ring brush 108 also contacts and abrasively cleans the inner surface of a surrounding wellbore (typically casing) during use.

A “reverse” circulation flow path described herein is used, as opposed to conventional “forward” circulation, for a variety of beneficial reasons including, without limitation, the following: such reverse circulation permits the capture of debris larger in size than the clearance between a workstring outer diameter and a wellbore internal diameter; such reverse circulation allows velocity control of well fluids used to transport debris by controlling the exact size of the flow area, regardless of the casing size; such reverse circulation permits capture of debris internally without having to flow around the outer diameter of the assembly, thereby risking the debris packing off and sticking the assembly in the wellbore; such reverse circulation creates of high volume fluid flow without having a high differential pressure in the area of debris collection, which can be critically important for recovering debris over sensitive items in the wellbore such as a formation isolation valve, retrievable packer plug or other similar equipment; and such reverse circulation provides the ability to capture debris in a relatively small section of wellbore (versus attempting to circulate debris out of a wellbore over a much longer distance).

Debris is removed from the well fluid stream using at least one filter sub assembly or FSA 200, typically connected to the bottom of RCSA 100. Said FSA 200 has a screen, slot(s), or other similar filtering device, as well as a magnet for capturing ferrous materials. Multiple FSA's can be utilized such as, for example, when multiple successive filtration subs are used to capture smaller and smaller debris. In the event that said at least one FSA 200 becomes blocked or clogged with debris, a bypass feature can activate, allowing fluid circulation to bypass said at least one FSA 200.

FIG. 3 depicts a side sectional view of a filter sub assembly, or FSA, 200 of the present invention. In a preferred embodiment, said FSA 200 connects to the base of said RCSA 100 (depicted in FIGS. 1 and 2) using drill-string threaded shoulder connection. FSA 200 generally comprises: top sub 201, screen assembly 202, screen centralizer 203, magnet housing 204, burst disc assembly 205, outer housing 207, annular debris chamber 208, bottom sub 209, debris tube 210, eccentrically centered debris diverter 211, debris removal sleeve 212, locating pin 213, magnet assembly end cap 214, cylindrical magnet 215, and magnet assembly centralizer 216.

Still referring to FIG. 3, bottom sub 209 has central through bore 220 and lower (male) pin-end threaded connection 219. Lower threaded connection 219 can be used to connect FSA 200 to lower components of the debris collection assembly of the present invention (such as, for example, a VSA). Well fluids flow from the bottom of said FSA 200 thru central through bore 220 of bottom sub 209 and into central bore 221 of debris tube 210.

Said fluid exits the upper opening of debris tube 210 and flows into an annular debris chamber 208 formed between the inner surface of housing member 207 and the outer surface of debris tube 210. Solid debris will frequently settle out within debris chamber 208 as well fluids flow out of the upper opening of debris tube 210 toward the upper portion of FSA 200.

Any remaining debris within said well fluids (that is, debris that did not settle within debris chamber 208 upon exiting debris tube 210) passes by and can be captured by a magnet assembly (including, without limitation, cylindrical magnet 215, magnet housing 204, magnet assembly end cap 214 and magnet assembly centralizer 216) if ferrous. Any remaining debris within said well fluids (that is, debris not captured by said magnet assembly) flows through a screen assembly 202 (such as a rod-based wire wrapped screen having screen centralizer 203) or other porous filter. Cleaned well fluids flowing through said screen assembly 202 continue flowing through central flow bore 222 of top sub 201, and eventually back to RCSA 100, while solid debris separated by said screen assembly 202 can fall back into debris chamber 208.

The configuration of debris tube 210 and annular debris chamber 208 is designed to allow debris laden fluid to enter said annular debris chamber 208 above settled solid debris, rather than flowing through already trapped debris within said debris chamber 208. An e-centered debris diverter 211 is located at or near the top of debris tube 210 to deflect debris toward the inner surface of housing member 207, imparting a rotational velocity to said fluid. Such rotational velocity helps separate heavy debris from a well fluid stream. Said debris tube 210 is also beneficially positioned near one side of debris chamber 208 to create a beneficially large annular space between the inner surface of housing member 207 and the outer surface of debris tube 210.

In the event that a debris particle size is slightly less than the full internal diameter of flow bore 221 of debris tube 210, said debris can nonetheless be received within annular debris chamber 208 due to said offset placement of debris tube 210 (which would not be possible with placement of debris tube 210 concentrically relative to housing member 207 and centered within debris chamber 208). Such offset placement allows for capture of larger debris particles.

Screen assembly 202 is used to filter fine particles from well fluids. Screen opening size can be altered or adjusted for particular applications. Similarly, multiple screens can be stacked to create a cascading filtration effect. A frangible burst disc assembly 205 can be beneficially located within a port 217 positioned between upper threaded connection 206 of top sub 201 and the upper portion of screen assembly 202.

In the event that said screen assembly 202 plugs or clogs, a fluid pressure differential will be created across disc assembly 205; when said pressure differential reaches a predetermined level, said disc assembly 205 can rupture. Rupturing of said disc assembly 205 permits fluid circulation to continue through port 217 even if said screen assembly 202 plugs or clogs, and can alert an operator when a fluid pressure spike is observed at the earth's surface. The rupture pressure of said burst disc assembly 205 can be configured for a given application and/or screen assembly.

An axial internal debris removal sleeve 212 is moveably disposed at or near the base of debris chamber 208. Said sleeve 212 is moveable axially, such that it can be shifted upwards to empty captured debris from debris chamber 208 via debris removal port 223 after said FSA 200 has been retrieved to the earth's surface. In a preferred embodiment, said sleeve has a plurality of positions including, without limitation: closed, vent fluid only, and vent debris. Axial positions of sleeve 212 can be controlled by locating pins 213 that can be manipulated by a user.

Debris collection and removal from within a wellbore can be verified by means of at least one camera positioned within a video sub assembly, or VSA, 300 having a desired field of vision. In a preferred embodiment, said VSA 300 comprises a body member or housing 301 having a central through bore 310 for permitting fluid and associated solid debris to be circulated through said VSA 300. Said body member 301 further comprises an elongate slot (ideally integrally machined in said body member) defining a chamber 311 for receiving a video camera 302 (or other optical sensor). It is to be observed that at least one additional slot may be machined in said body member 301 to define chamber(s) for receiving additional memory, camera devices and/or power supply/batteries for extended operating time downhole within a wellbore.

Camera 302 has a field of vision directed at debris laden well fluid circulated through said VSA 300. Camera 302 can be illuminated by a lighting device, or a lighting system, disposed parallel with said camera 302, or in any manner that agrees with a desired field of view of said camera 302. Additionally, said camera 302 of the present invention can comprise an electronic memory chip or other memory device that beneficially provides said camera with sufficient memory to record and store a plurality of visual images, photographs or videos that can be reviewed for validation of wellbore cleanliness and effectiveness of debris removal operations.

By way of illustration, but not limitation, retrieval of visual images and/or video data from said debris collection assembly can be accomplished by a variety of different methods, such as for example: wireless transmission of data from said VSA 300 to a recording/display device, particularly at or near the earth's surface; transmission of data from said VSA 300 to a recording/display device via a wired connection, particularly at or near the earth's surface; direct extraction or download of data from electronic memory of said VSA 300 to a separate electronic memory device via wired or wireless data transmission; and/or transmission of data from said VSA 300 to a receiver conveyed on wireline and positioned in proximity to said debris collection assembly via wired or wireless transmission.

VSA 300 can include a rotatable external sleeve 303 that constrains said camera 302 (and extra battery packs, memory, etc.) within chamber 311 defined in body member 301, while permitting convenient access to said components when VSA 300 is on surface. Said rotatable external sleeve 303 includes a beneficially positioned elongate aperture having approximately the same width and length dimensions as downhole camera 302. When access to said camera 302 is desired, said external sleeve 303 can be rotated into alignment with camera 302 so that said camera 302 is accessible through said elongate aperture, such as for removal or maintenance of camera 302 and/or associated equipment.

External sleeve 303 can rotate relative to body member 301, but said components are axially fixed relative to each other. At least one transverse bore 308 is formed in body member 301. A trapped set screw 307 and compression spring 309 is disposed within each such transverse bore 308. Mating holes in external sleeve 303 correspond to said trapped set screws. When extended, said set screws 307 are partially received within said holes in sleeve 303, thereby locking said sleeve 303 against rotational movement. When desired, set screw(s) 307 can be recessed inward within transverse bores 308, thereby permitting sleeve 303 to rotate (such as, for example, to install or remove camera 302 from body member 301.

In a preferred embodiment, the outer diameter of each set screw fastener 307 is larger than the diameter of a corresponding access hole in sleeve 303. Each set screw fastener 307 is fully threaded into transverse bores 308 before sleeve 303 is installed, and then backed out to lock said sleeve 303 against rotation. Compression spring 309 is installed below each trapped set screw 307 to bias said set screw 307 outward and prevent said set screw 307 from backing out from sleeve 303 downhole due to vibration.

The debris collection assembly of the present invention can also be run in combination with other data sensors, in addition to a camera. Additionally, the debris collection assembly of the present invention can be powered by any number of different methods including, but not necessarily limited to, surface fluid pump pressure, manipulation of a tubular workstring, and/or downhole fluid pump(s) located within said assembly. Placement of a camera (directly above debris) allows for optimal view of before and after debris clean-up.

Said VSA 300 further comprises a wash over type mule shoe 304 that can be used to guide debris into central flow bore 310 of said VSA 300. Said wash over mule shoe 304 is beneficially replaceable so different combinations of length, internal diameter and external diameter can be used to accommodate a particular application. Said mule shoe 304 is fixed in place using a thread and locked rotationally using trapped fasteners.

A high strength lens 305—typically constructed of plastic—is disposed between the inner through bore 310 of the VSA 300 and camera 302 to protect said camera 302 from impact. A molded rubber or elastomeric vibration isolator 306 further protects camera 302 from vibration and shock. In a preferred embodiment, said isolator 306 is split so that it can fit over the external surface of camera 302 and is molded to match the annulus formed between the camera 302 and chamber 311 formed in body member 301. Box-end threaded connection 312 can be used to threadedly connect VSA 300 to other components of the debris collection assembly of the present invention (such as a FSA 200).

In operation, debris collection assembly of the present invention comprises an uppermost RCSA 100, a VSA 300, and at least one FSA 200 disposed between said RCSA and VSA. Said components are typically threadedly connected to a tubular workstring (frequently at the lower or distal end of said work string) and conveyed into a wellbore.

Well fluids are pumped into an internal flow bore of a tubular workstring, typically from surface fluid pumps. Said well fluids exit said workstring, enter the inner bore of RCSA 100, and are diverted through said RCSA 100 into an annular space formed between the outer surface of said RCSA 100 and the inner surface of the surrounding wellbore. Said well fluids displace existing well fluids (typically containing debris to be removed) through said annular space and, eventually, into mule shoe 304 of VSA 300; debris is carried by increased fluid velocity into central flow bore 310 of VSA 300.

Debris collection and removal from within a wellbore can be verified by camera 302 beneficially positioned within said VSA 300. By way of illustration, but not limitation, said at least one camera 302 can be positioned adjacent to internal flow bore 310 extending through said VSA 300, such that well fluids and accompanying debris entering said internal flow bore 310 can be sensed (typically via visual images and/or video) and recorded. The field of vision of said at least one camera 302 can be illuminated by a lighting device, or a lighting system, typically disposed parallel with said at least one camera 302, or in any manner that agrees with a desired field of view of said camera.

Well fluids and associated debris are circulated through said central bore 310, leave said VSA 300 and enter at least one FSA 200 via central flow bore 220 of bottom sub 209. Said solid debris is removed from said well fluid stream using at least one FSA 200 having a screen, slot(s), or other similar filtering device, as well as a magnet for capturing ferrous materials, as described in more detail above. Multiple FSA's 200 can be utilized such as, for example, when multiple successive filtration subs are to capture smaller and smaller debris.

After debris removal, clean fluid exits said at least one FSA 200 via central flow bore 222 of top sub 201 and re-enters RCSA 100 via through bore 120 of bottom sub 105. Said fluid is redirected by said RCSA 100 to the annular space formed between the outer surface of said tubular workstring and the inner surface of the surrounding wellbore and can thereafter return to the earth's surface via a conventional wellbore circulation path through said workstring/casing annular space. The process can be repeated until desired results are obtained.

The debris collection assembly of the present invention has a number of important benefits. Said debris collection assembly allows for simplified use with few, if any, moving parts. Further, said debris collection assembly does not rely on a jet-pump or other downhole fluid pump to create reverse circulation, thus allowing for a longer bottom hole assembly. The modular components of the debris collection assembly of the present invention can be joined using “quick connect” threads between said components, thereby allowing for easier and more efficient manipulation on a rig floor.

The above-described invention has a number of particular features that should preferably be employed in combination, although each is useful separately without departure from the scope of the invention. While the preferred embodiment of the present invention is shown and described herein, it will be understood that the invention may be embodied otherwise than herein specifically illustrated or described, and that certain changes in form and arrangement of parts and the specific manner of practicing the invention may be made within the underlying idea or principles of the invention. 

What is claimed:
 1. A method for visually-monitored downhole removal of solid debris from well fluid in a wellbore, the method comprising the steps of: (a) inserting a debris collection assembly into a tubular workstring deployed in a wellbore, the debris collection assembly comprising a reverse circulation sub-assembly (RCSA), a video sub-assembly (VSA), and a filter sub-assembly (FSA), the RCSA in internal flow bore communication with a surface supply of clean well fluid delivered to the RCSA via an internal flow passageway through the workstring; (b) positioning the debris collection assembly at a pre-determined wellbore location such that the debris collection assembly is adjacent debris in local well fluid in an annular space separating the debris collection assembly from the wellbore; (c) sealing the annular space so as to create a predetermined well fluid flow pathway from the internal flow bore of the RCSA into the annular space, then through the VSA and the FSA, then back into the annular space and up to the surface; (d) passing clean well fluid from the internal flow bore of the RCSA, through the RCSA, and into the annular space; (e) diverting, via well fluid flow, debris in the annular space into an internal VSA pathway in the VSA; (f) acquiring, as the debris passes through the internal VSA pathway; visual data regarding the debris with a video camera assembly mounted inside the VSA; (g) processing the visual data; (h) diverting, again via well fluid flow, the debris out of the internal VSA pathway and into an internal FSA pathway in the FSA; and (i) collecting the debris in the FSA as it passes through the internal FSA pathway.
 2. The method of claim 1, in which step (c) includes the substeps of: (c1) providing a radially-extendable annular brush ring on the RCSA; (c2) extending the brush ring so as to seal the annular space, and (c3) selectively cleaning an internal surface of the wellbore with the brush ring.
 3. The method of claim 1 or 2, in which the visual data includes data selected from the group consisting of (1) still pictures, and (2) motion video, and in which step (g) includes the substeps of: (g1) storing the visual data in local memory included in the video camera assembly; and (g2) telemetering first selected portions of the visual data to the surface.
 4. The method of claim 3, in which substep (g2) further includes the substeps of: (g2.1) sending second selected portions of the visual data to the surface in real time; and (g2.2) extracting third selected portions of the visual data from local memory and sending the third selected portions to the surface.
 5. The method of any of claims 1-4, in which step (i) includes the substep of: (i1) passing the debris through screens and slots.
 6. The method of any of claims 1-5, in which step (i) includes the substep of: (i2) passing the debris over magnets.
 7. The method of any of claims 1-6, in which the FSA comprises a plurality of individual filtration units in fluid flow series, and in which each filtration unit in the series is configured to collect successively smaller debris.
 8. The method of claim 7, in which step (i) includes the substep of: (i3) responsive to individual filtration units becoming clogged with debris, bypassing said clogged filtration units. 